Method of making a porous metal spinning ring

ABSTRACT

A powdered metal spinning ring in which the ring, after being initially formed in a press and sintered is then compressed circumferentially to taper the ring body so that the inner wall is in the form of an inverted truncated cone. The exterior of the ring is then machined in conventional manner after which the ring is heat treated and polished to be ready for use in a spinning frame.

ite gtates atet 1 7 Wayson et al. [45] July 18, 972

[ METHOD OF 1" G A POROUS 3,370,947 2/1968 Talmage ..29/420.s x

METAL SPWNING '1 s OTHER PUBLICATIONS 72 Inventors: Andrew Wa son N dh 1 Com L g Ex m T 0 Moore, Abstract of Serial No. 599,363, filed June 14, 1945,

published June 10, 1952 [73] Assignee: Merriman, Inc., Hingham, Mass.

Primary Examiner-John F. Campbell [22] Flled' 1970 Assistant Examiner-Donald C. Reiley, III [21] Appl. No.: 88,262 Attorney-Robert S. Smith, Esq., David S. Urey, Alan C.

Rase and Alfred B. Levine [52] U.S. Cl. .29/420.5, 29/DlG. 31, 72/347 57] ABSTRACT [51] Int. Cl. ..B22f 3/24 [58] Held of Search ..29/420.5, 527.1, DIG. 31; A PWdered metal spmmng whlch after bemg 72 /3 47 initially formed in a press and sintered is then compressed circumferentially to taper the ring body so that the inner wall is 56] References Cited in the fon'n of an inverted truncated cone. The exterior of the ring is then machined in conventional manner after which the UNITED STATES PATENTS ring is heat treated and polished to be ready for use in a fr 275,938 4/1883 Parker 72/347 spmnmg ame 325,692 9/1885 Parker ..72/347 X 4 Claims, 6 Drawing figures a8 a 14 n2 l\\ 5 Q l b Patented July 18, 1972 3,676,917

2 Sheets-Sheet l Patented July 18, 1972 3,676,917

2 Sheets-Sheet 2 METHOD OF MAKING A POROUS METAL SPINNING RING BACKGROUND OF THE INVENTION Spinning rings made of powdered metal in which the metal particles have been compressed in a die under very high pressure in the order of 30 tons psi have been in use for many years in the textile industry and their self-lubricating properties are well understood in the art. The ring, after its initial formation in the die, is sintered to cause agglomeration of the metal particles into a stronger structure. Then, the ring is machined on its inner and outer walls to give the proper configuration and dimensions. Following the machining operation, the ring is heat treated to improve the wearing characteristics of the surface without impairing the oil transmitting properties. Polishing is the final operation.

In the patent to Wayson U.S. Pat. No. 3,41 1,286 of Nov. 19, 1968 is shown a powdered metal spinning ring manufactured according to the process described briefly above. It will be noted in this patent that the inner wall of the horizontal type spinning ring disclosed slopes upwardly and outwardly. It will be appreciated by those persons familiar with the molding art, that a molded ring of this configuration could not be made directly by molding because of the negative taper of the inner wall. For this reason, the ring of the Wayson patent was molded initially with a substantially vertical inner wall after which machining produced the upward outwardly sloping inner wall.

The present invention contemplates a process whereby an inner sloping wall like that of the Wayson patent can be produced without the necessity of machining the inner wall. The absence of machining is advantageous because it has been found that when the surface of a product made of powdered metal is machined through the use of conventional cutting or grinding tools, the agglomerated particles are rearranged or reshaped in such manner as to render the surface less porous than it was before the machining operation. By the use of the process herein disclosed and claimed, a sloping inner wall whose porosity remains substantially unchanged from its condition as originally molded can be produced without machining. Not only is the resulting spinning ring made by this new process superior in its oil transmitting characteristics at the critical areas, but it is also less expensive to make and the dimensions of the finished ring may be held within closer tolerances.

The preferred method of carrying out the shaping process to produce the improved ring is through the use of a tapered female die into which the basic unmachined molded and sintered ring is forced to cause the inner and outer walls to be changed from their original shapes which ordinarily would be substantially cylindrical surfaces to short truncated conical surfaces. The outer wall surface, during the shaping process, is in sliding compressive engagement with the die. The inner wall surface of the ring, however, is shaped without engagement with any tool to assume the truncated conical form.

After the ring body has been shaped in the manner just described, it is removed from the die by an ejector. Then the exterior portion of the ring is subjected to conventional machining operations to produce the final required configuration. Final finishing and polishing operations are then performed along with the necessary drilling or cutting of oil passages in the body of the ring and if desired the cutting of a circular oil groove in the top of the ring.

The tapering of the ring may also be achieved by the use of other known mechanisms capable of causing reduction in circumference of cylindrical elements. One such mechanism could be a set of tapered rolls appropriately spaced into which the ring could be forced while rotating to be deformed to the required shape. Again in this procedure, the inner wall of the ring would be untouched by any tools and hence its porosity would be unaffected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional elevation of a horizontal type spinning ring in its original molded condition.

FIG. 2 illustrates the ring of FIG. I positioned above a die into which it is about to be forced.

FIG. 3 shows the ring of FIGS. 1 and 2 forced into the die thereby to assume a new configuration in which the inner and outer walls are tapered.

FIG. 4 is illustrative of the original ring modified according to the step shown in FIG. 3 with its exterior turned to give the ring the exact required final configuration.

FIGS. 5 and 6 illustrate an alternative mechanism for carrying out the method of tapering the inner and outer walls of the ring.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1 in the drawings, there is illustrated in preliminary form in vertical cross-section a molded horizontal type spinning ring 2 made of highly compressed metal particles. The method of making such ring is well understood in the industry. The powdered metal is subjected to pressures in the order of 30 tons psi which is sufficient to create an initially stable article. The ring after removal from the mold is subjected to a sintering operation in which the minute metal particles agglomerate to produce a much stronger unit but without destroying the basic porosity. In quite general terms, the total volume of a molded spinning ring made from highly com pressed powdered metal may consist of about of solid particles and the remaining 20 percent of the total volume is represented by continuous passages between the particles through which the lubricating oil may travel to spread itself ultimately on the ring surface thereby to provide the required lubricating film at those areas which are engaged by the rotating traveler.

The sintering process strengthens the ring to such degree that it then has characteristics that make subsequent machining and limited deforming operations possible without likelihood of fracture of the agglomerated material.

On further reference to FIG. 1, it will be noted that the inner wall 4 and the outer wall 6 are substantially short cylindrical sections. For molding reasons, one or the other or both walls must have some positive taper to permit the molded ring to be removed from the die. Any negative taper on either of the ring walls would make removal of the ring from the dies impossible, unless the dies were of the split type which is not only structurally undesirable, but also undesirable from the standpoint of creating vertical seams in the related walls.

It should also be noted that the lower surface 8 of the ring has a slight downward inward slope as do the upper and lower surfaces 10 and 12, respectively, of the inner flange 14 of the ring.

The second step in the process is preferably carried out through the use of a circular die 16 having a tapered female aperture 18 whose upper dimension as at 20 is sufficient to allow the starting entry of ring 2 therein. With the ring 2 in position as shown in FIG. 2, a pressing element 22 is moved downwardly to engage the top of the ring 2 to force the ring into the die 16 as illustrated in FIG. 3. The outer wall 6 of the original ring is thus deformed to a truncated conical shape 24 as shown in FIG. 3 and the inner wall 4 of the ring which was originally substantially cylindrical as shown in FIG. 1 is correspondingly changed to an inverted truncated conical formation 26 substantially parallel to the outer conical surface 24.

It is apparent in FIG. 3 that the circumference of ring 2 at the bottom portion 28 is less than the circumference of the ring at its upper portion 30. Thus, it is thought to be obvious that the metal particles of which the ring is formed are compacted in the construction in FIG. 3 in increasing degree from the upper level 30 to the lower most level 28. This being the case, the porosity of the inner wall of the ring is slightly less at its bottom than at its top which is an advantage as it reduces the flow of oil to the lower wall surface where oil is not needed, thus to minimize leakage. This decrease in porosity, however, does not have any adverse effect on the functioning of the ring as the area of engagement of the traveler with the ring is at the underside 12 of the inner flange l4 and the upper inner wall surface as at 32 of the ring body portion 34 whose porosity has remained substantially unchanged.

The pressing element 22 acts quickly to force ring 2 from its position above die 16 into the die as illustrated in FIG. 3. The pressing element 22 is then raised a sufficient distance above die 16 and an ejector 36 moves upwardly to force the ring 2 out of die 16.

It will be noted further in FIG. 3 that the bottom surface 8 of ring 2 which was originally slightly conical now lies substantially in a plane transverse to the axis of the die and the ring. Likewise, the top and bottom surfaces of the ring flange 14 have been modified slightly to lie substantially in a transverse plane.

The ring on removal from die 16 is then machined on its exterior to produce the finished ring shown in FIG. 4. The body 34 is narrowed as at 38 to create the outer flange 40 which in cooperation with the existing inner flange 14 acts to carry a conventional traveler. Oil groove 42 may be cut in the top of the ring and oil passages 44 and 46 may be drilled to provide means for transmitting oil to the oil groove. The tapered inner wall 26 of the ring, as well as the underside 12 of inner flange 14 remains untouched by any tools during the change in configuration from that shown in FIG. 1 to that shown in FIGS. 3 and 4. Because this tapered inner wall 26 is not touched by any tools, the original porosity of the ring surfaces at the areas 12 and 32 where the inner end of the traveler makes engagement with the ring is not diminished. Furthermore, the surface of inner wall 26 and underside 12 of flange 14, which, on leaving the dies after the original molding operation, are in smooth condition, remains just as smooth so that no polishing operations are required.

The novel method of creating the negative tapered conical formation of the inner wall produces a ring having characteristics not available when made to the required finished form according to previous practices. The invention thus contemplates not only a new method of creating the ring, but also a new ring in which the critical porous surfaces retain a porosity undiminished because of the absence of subsequent machining operations.

While the preferred method of creating the short truncated conical inner and outer wall surfaces is through the use of a die such as illustrated in FIGS. 2 and 3, it will be appreciated that the method is not to be limited to any single mechanism capable of achieving the desired result. Accordingly, a second mechanism for carrying out the method is illustrated in FIGS. and 6. Under this procedure, the ring 2 is placed in engagement in engagement with three tapered rolling elements 48, 50 and 52 mounted for rotation on shafts 54, 56 and 58, respectively. A rotating pressing element 60 whose axis 62 is aligned with the axis of ring 2 descends to force the rotating ring 2 downwardly between rolls 48, 50 and 52 thereby to gradually deform the cylindrical body of the ring into a conical body 64 similar to the configuration of the ring shown in FIG. 3. The subsequent steps performed on ring 2 after it has been shaped by the mechanism of FIGS. 5 and 6 are the same as those heretofore described.

The angle of the inner wall of the ring body to the vertical v may be in the order of 6, but this may be any negative angle as pointed out in the patent to Wayson US. Pat. No. 3,41 I286 previously referred to herein.

It will be understood that when the term tapered die is used in the method claims appended hereto, it is intended to include any means capable of deforming the body of the initially molded ring so that the inner wall is shaped to a negative taper without any machining or modification of the wall surface, thus to leave the inner wall porosity undiminished.

It is intended to cover all changes and modifications of the examples of the invention herein chosen for purposes of the disclosure which do not constitute departures from the spirit and sco e of the invention.

We c arm:

1. A method of making a porous metal spinning ring comprising the steps of compressing powdered metal in a mold to form a traveler supporting body having inner and outer walls and an inner circular flange adjacent the upper part of said inner wall, removing the ring from the mold, forcing the ring into a tapered die to shape the said walls into the form of short truncated cones without appreciably changing the porosity of that part of the inner wall adjacent said inner flange, removing the ring from said die, and machining the ring to the required final ring configuration without changing the under surface of said inner flange or the inner wall surface adjacent said inner flange 2. The method set forth in claim 1, said ring being sintered after being removed from the said mold and before being forced into said die.

3. A method of making a porous metal spinning ring comprising the steps of compressing powdered metal in a mold to form a traveler supporting body having inner and outer walls neither of which has negative draft and said inner wall is sub stantially cylindrical, removing the ring from the mold, sintering said ring, forcing the ring into a tapered die to deform the outer wall into the form of a short truncated cone and to cause the inner wall to assume an analogous shape without appreciably changing the porosity of that part of the inner wall adjacent said inner flange, removing the ring from said die, and machining the ring to the required final ring configuration without changing the under surface of said inner flange or the inner wall surface adjacent said inner flange.

4. A method of forming an inverted truncated conical inner wall in a molded sintered powdered metal spinning ring which ring initially has been formed with substantially cylindrical inner and outer walls, said method comprising the steps of forcing said ring into a tapered die whose shape is analogous to the required final shape of the inner wall of the ring, the forcing of said ring into said die being accomplished by applying pressure to the top circular surface of said ring in a direction parallel to the die axis whereby the inner wall will be untouched during the shaping and the porosity of the inner wall at its upper part will remain substantially unchanged from its original molded condition. 

2. The method set forth in claim 1, said ring being sintered after being removed from the said mold and before being forced into said die.
 3. A method of making a porous metal spinning ring comprising the steps of compressing powdered metal in a mold to form a traveler supporting body having inner and outer walls neither of which has negative draft and said inner wall is substantially cylindrical, removing the ring from the mold, sintering said ring, forcing the ring into a tapered die to deform the outer wall into the form of a short truncated cone and to cause the inner wall to assume an analogous shape without appreciably changing the porosity of that part of the inner wall adjacent said inner flange, removing the ring from said die, and machining the ring to the required final ring configuration without changing the under surface of said inner flange or the inner wall surface adjacent said inner flange.
 4. A method of forming an inverted truncated conical inner wall in a molded sintered powdered metal spinning ring which ring initially has been formed with substantially cylindrical inner and outer walls, said method comprising the steps of forcing said ring into a tapered die whose shape is analogous to the required final shape of the inner wall of the ring, the forcing of said ring into said die being accomplished by applying pressure to the top circular surface of said ring in a direction parallel to the die axis whereby the inner wall will be untouched during the shaping and the porosity of the inner wall at its upper part will remain substantially unchanged from its original molded condition. 